Welding rod



Patented Apr. 22, 1941 WELDING ROD Agostino Nepoti, Sesto Calende,Varese, Italy No Drawing. Application December 13, 1938, Serial No.245,506. In Italy December 14, 1937 2 Claims.

The present invention relates to an electrode for electric arc welding,consisting of special materials having high resistance, high coefficientof percentage lengthening and high resilience and which does not havestructural modifications caused by thermal actions and therefore do notcause variations of the mechanical characteristics.

Electrodes for arc welding employed heretofore present severaldisadvantages which are overcome by the present invention.

The alloy constituting the material to be deposited for the welding,according to the present invention, does away with the disadvantages andis characterized by a very low content of carbon, a greater percentageof manganese and the addition of improving components such as the Si, Crand Mo.

The reduction in the percentage of C serves to prevent the structuralvariations of hardening due to the high velocity of cooling especiallyin the first layer of the deposited material; such reduction, however,would tend to simultaneously diminish the resistance of the addedmaterial and to lower its elastic limit. The presence of a greaterpercentage of manganese'which, however, must not be too high as,otherwise, the various disadvantages of structural variations wouldappear, partially prevents the reduction of the resistance.

The addition of Si reestablishes the value of the elastic limit.

The Cr and the molybdenum are added within certain limits as improvingelements in relation to the welding.

The Ni may also be added as a stabilizing element for the structure, andto improve the mechanical characteristics of. the material; suchaddition does, however, influence the characteristics and theparticularities of the alloy under the point of view of the invention.

Particularly the alloy according to the present invention ischaracterized by the reciprocal proportions of constituents.

For the purpose of enabling one skilled in the art to practice theinvention an average composi tion is given, by way of example only, ofthe ma Per cent C 0.08 to 0.11 Mn 1.2 to 1.4 Si 0.25 to 0.35 Cr 0.55 to0.75 Mo 0.25 to 0.35

iii

terial for an electrode according to the present invention, whichpresents a resistance of 72 kgs./sq. mm. and a lengthening coefilcientof 22% determined with a small bar of circular crosssection, having alength equal to five times its diameter.

As aforesaid, an addition of Ni from 0.15 to 0.25% may be made for theindicated purposes.

If, for the constitution of an electrode which may be bare-orprotectively covered, the material indicated above is employed, severaladvantages are realized and especially, for weldings on high resistancesteel (beyond kgs./sq. mm.) total insensibility to thermal actions,possibility of electrodes which, through slight modifications of thepercentages indicated above by way of example, may reach, without anythermal treatment, very high coeillcients of resistance up to 110kgs./sq. mm; an absolute homogeneity for all the layers of depositedmaterial at the welding seam, and particularly a high value of thelengthening coeillcient which will remain the same for the materialconstituting the first layers upon steels of very high resistance; inthis manner the shrinkage tensions will be eliminated as they areabsorbed by the lengthening of the deposited material, further alsocracks will be done away with, and it will be possible to effectweldings also upon very large structures, the whole without anynecessity of normalization, the value of the resilience oi the weld willbe maintained unaltered and high, the hardened Zones of welding will beeliminated and better conditions of operation and of practical resultswill be realized carrying out weldings hitherto thought impossible(higr. resistance armours).

Having now described my invention what I claim is:

1. A welding rod consisting of 0.08 to 0.11% carbon, 1.2 to' 1.4%manganese, 0.55 to 0.75% chromium, 0.25 to 0.35% molybdenum andremainder iron, said rod giving a welding line having a tensile stressof to kg./mm., the material constituting said welding line beingresistant to the customary hardening thermal treatments.

2. A welding rod consisting of 0.08 to 0.11%

carbon, 1.2 to 1.4% manganese, 0.55% to,0.75%.

chromium, 0.25 to 0.35% molybdenum, 0.25 to 0.35% silicon and theremainder iron.

